The set of 231 plastic pieces costs about $US25 and went on sale Wednesday morning. Its instant popularity is not surprising to those who have been following Lego’s laudable — and presumably profitable — trend of selling toys that are more inclusive of women.

“Women of NASA” features four mini figurines of pioneering women from the space agency: the astronauts Sally Ride and Mae Jemison, the astronomer Nancy Grace Roman, and the computer scientist Margaret Hamilton.

Each figurine comes with her own backdrop of relevant NASA work, including a mini-space shuttle Challenger for the astronauts and a mini-Hubble Space Telescope.

The toy set has a grassroots origin story. Maia Weinstock, a deputy editor at MIT News, submitted her idea for the product to Lego’s Ideas community in July 2016. Members on that site create and vote on other users’ plans; if Lego picks the idea, creators get a 1% cut of sales and licensing revenue.

One figurine is missing from Weinstock’s original kit proposal, though: Katherine Johnson, a mathematician at NASA whose remarkable story of working on the Mercury and Apollo programs was the focus of the film “Hidden Figures.”

“In order for us to move forward with a partner we need to obtain approval from all key people, which was not possible in this case. We naturally fully respect this decision,” a Lego representative told Gizmodo in an Oct. 25 story.